#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>

using namespace std;


class BearPlaysDiv2 {

	void sort_triple(int & a, int & b, int & c)
	{
		if (a > b) swap(a, b);
		if (a > c) swap(a, c);
		if (b > c) swap(b, c);
	}

public:
	string equalPiles(int a, int b, int c) {
		long long sum = a + b + c;
		if (sum % 3) return "impossible";
		set<pair<int, int> > vis;
		sort_triple(a, b, c);
		queue<pair<int, int> > q;
		q.push(make_pair(a, b));
		int const max_trans = 1000000;
		for (int count = max_trans; count && !q.empty(); count--) {
			pair<int, int> now = q.front(); q.pop();

			if (now.first == now.second && now.first * 3 == sum)
				return "possible";

			{
				int a = now.first, b = now.second, c = sum - a - b;
				b -= a;
				a *= 2;
				sort_triple(a, b, c);
				pair<int, int> tmp = make_pair(a, b);
				if (vis.find(tmp) == vis.end()) {
					q.push(tmp);
					vis.insert(tmp);
				}
			}
			{
				int a = now.first, b = now.second, c = sum - a - b;
				c -= a;
				a *= 2;
				sort_triple(a, b, c);
				pair<int, int> tmp = make_pair(a, b);
				if (vis.find(tmp) == vis.end()) {
					q.push(tmp);
					vis.insert(tmp);
				}
			}
			{
				int a = now.first, b = now.second, c = sum - a - b;
				c -= b;
				b *= 2;
				sort_triple(a, b, c);
				pair<int, int> tmp = make_pair(a, b);
				if (vis.find(tmp) == vis.end()) {
					q.push(tmp);
					vis.insert(tmp);
				}
			}
		}
		return "impossible";
	}
};

// BEGIN KAWIGIEDIT TESTING
// Generated by KawigiEdit 2.1.4 (beta) modified by pivanof
bool KawigiEdit_RunTest(int testNum, int p0, int p1, int p2, bool hasAnswer, string p3) {
	cout << "Test " << testNum << ": [" << p0 << "," << p1 << "," << p2;
	cout << "]" << endl;
	BearPlaysDiv2 *obj;
	string answer;
	obj = new BearPlaysDiv2();
	clock_t startTime = clock();
	answer = obj->equalPiles(p0, p1, p2);
	clock_t endTime = clock();
	delete obj;
	bool res;
	res = true;
	cout << "Time: " << double(endTime - startTime) / CLOCKS_PER_SEC << " seconds" << endl;
	if (hasAnswer) {
		cout << "Desired answer:" << endl;
		cout << "\t" << "\"" << p3 << "\"" << endl;
	}
	cout << "Your answer:" << endl;
	cout << "\t" << "\"" << answer << "\"" << endl;
	if (hasAnswer) {
		res = answer == p3;
	}
	if (!res) {
		cout << "DOESN'T MATCH!!!!" << endl;
	} else if (double(endTime - startTime) / CLOCKS_PER_SEC >= 2) {
		cout << "FAIL the timeout" << endl;
		res = false;
	} else if (hasAnswer) {
		cout << "Match :-)" << endl;
	} else {
		cout << "OK, but is it right?" << endl;
	}
	cout << "" << endl;
	return res;
}
int main() {
	bool all_right;
	all_right = true;
	
	int p0;
	int p1;
	int p2;
	string p3;
	
	{
	// ----- test 0 -----
	p0 = 10;
	p1 = 15;
	p2 = 35;
	p3 = "possible";
	all_right = KawigiEdit_RunTest(0, p0, p1, p2, true, p3) && all_right;
	// ------------------
	}
	
	{
	// ----- test 1 -----
	p0 = 1;
	p1 = 1;
	p2 = 2;
	p3 = "impossible";
	all_right = KawigiEdit_RunTest(1, p0, p1, p2, true, p3) && all_right;
	// ------------------
	}
	
	{
	// ----- test 2 -----
	p0 = 4;
	p1 = 6;
	p2 = 8;
	p3 = "impossible";
	all_right = KawigiEdit_RunTest(2, p0, p1, p2, true, p3) && all_right;
	// ------------------
	}
	
	{
	// ----- test 3 -----
	p0 = 18;
	p1 = 18;
	p2 = 18;
	p3 = "possible";
	all_right = KawigiEdit_RunTest(3, p0, p1, p2, true, p3) && all_right;
	// ------------------
	}
	
	{
	// ----- test 4 -----
	p0 = 225;
	p1 = 500;
	p2 = 475;
	p3 = "possible";
	all_right = KawigiEdit_RunTest(4, p0, p1, p2, true, p3) && all_right;
	// ------------------
	}
	
	if (all_right) {
		cout << "You're a stud (at least on the example cases)!" << endl;
	} else {
		cout << "Some of the test cases had errors." << endl;
	}
	return 0;
}
// END KAWIGIEDIT TESTING

//<%:testing-code%>
